Recently, in assembly manufacturing processes of various industrial products or home electric appliances, or in device manufacturing processes of various electronic components, various batteries or substrates to be component parts of these products, heating treatment is performed by various heat treatment apparatuses after applying paste materials having various functions. Here, various heat treatment apparatuses are, for example, a drying furnace, a firing furnace, a curing furnace or a renew furnace used for soldering in a mounting process of electronic components and so on. In respective paste materials, in addition to the adjustment of a solid content finally required for the products, the viscosity adjustment or the performance adjustment is performed by mixing various types of solvents such as water or organic solvents in accordance with respective objects or necessities for applying these pastes to various types of substrates or base materials.
These solvents are discharged into the apparatus from the paste materials through vaporizing and desolvation processes in the heating process in the heat treatment apparatus. Accordingly, in the case where the heating treatment is repeatedly performed, the solvent is continuously vaporized and discharged in the apparatus, as a result, a solvent concentration in an atmosphere inside the apparatus is increased, which say lead to various problems. For example, the amount of the solvent which can exist in the atmosphere at a temperature inside the apparatus becomes close to the saturation as the solvent concentration in the atmosphere inside the apparatus is increased, which makes the drying of an object to be thermally treated difficult. Moreover, a vaporized solvent concentration may exceed explosion limits even when the solvent does not reach the saturated vapor pressure in the case of a solvent having an explosive nature. Therefore, it is necessary to supply outside air into the apparatus from the outside of the apparatus periodically or continuously, or if a nitrogen gas or other atmospheres (atmosphere gases) are necessary, it is necessary to supply these atmospheres from the outside of the apparatus. Furthermore, a means for discharging the atmosphere in the apparatus in which solvent concentration is increased to the outside of the apparatus is adopted at the same time.
FIG. 7 is a view for explaining supply and exhaust of the atmosphere. The outside air is supplied into a heat treatment apparatus 101 by an air blower 2. Part of the atmosphere inside the heat treatment apparatus 101 containing a solvent vaporized inside the heat treatment apparatus 101 is discharged to the outside of the apparatus by an exhaust blower 3. As a system of removing the vaporized solvent contained in the exhaust, particularly, water vapor, the system described in JP-A-2006-87972 (Patent Document 1) is known.
FIG. 8 is an explanatory view of Patent Document 1. A structure disclosed in Patent Document 1 is as follows. A charging electrode 4 and an attracting electrode 5 rotate around a first rotation axis 7 and a second rotation axis 8 respectively. The first rotation axis 7 and the second rotation axis 8 are respectively connected to a drive motor 6 through a first drive transmission belt 9 and a second drive transmission belt 10. The charging electrode 4 and the attracting electrode 5 rotate by the driving of the drive motor 6. In this case, through holes 4a are disposed in the charging electrode 4 and through holes 5a are disposed in the attracting electrode 5 respectively so that the contact area between the charging electrode 4/the attracting electrode 5 and an exhaust 117 is increased. In the system of Patent Document 1, when the solvent in the exhaust 117 to be supplied is vaporized, the solvent vaporized in an upper stream side of an exhaust flow path is charged by contacting the rotating charging electrode 4 and moves in a direction of the attracting electrode 5 in a lower stream side of the flow path, not by condensing the solvent by cooling. Then, the vaporized solvent is induced by the rotating attracting electrode 5 having charges of a reverse polarity to the polarity of the charged solvent, and the solvent is attracted to the attracting electrode 5. The solvent attracted to the attracting electrode 5 is collected by a water-drop collector 11 by a centrifugal force of the attracting electrode 5.